As a method for inducing and enhancing an antitumor effect in human lymphocytes, it has been known LAK therapy using interleukin-2. That is, it has been known that by having about 800 U/ml of interleukin-2 to act on the lymphocytes, cell groups induced thereby with an antitumor activity can be used as an antitumor effecter. However, in this method, there are serious side effects, for example, destruction of the self cells such as endovascular cells due to non-specific cytotoxic property possessed by LAK cells and the like or induction of autoimmunity due to non-specific activation of T cells by interleukin-2, thereby making it difficult to apply this methods to an actual clinical field.
As compounds which specifically activate Vγ2Vδ2 type T cells, there have been known mycobacteria-derived isopentenyl pyrophosphoric acid and mono ethyl phosphoric acid obtained by an organic synthesis. In those methods, however, the concentrations of those compounds are required to be several hundreds of μM to several mM in order to activate Vγ2Vδ2 type T cells. Such high concentrations of the compounds may have a toxic effect on the cells, therefore, it was difficult to use those compounds to induce and enhance an antitumor effect of the lymphocytes in a large scale. In any case, it has not yet been known a synthetic compound which can act on the Vγ2Vδ2 type T cells in a concentration of several hundreds of nM to several hundreds of μM, and specifically proliferate those cell groups.
The present invention has been aimed to solve the above-mentioned problems of the prior art. An object of the present invention is to provide a novel compound that can specifically stimulate and proliferate the human Vγ2Vδ2 type T cells, an agent for treating lymphocytes that induces and/or potentiates an antitumor effect of the human Vγ2Vδ2 type T cells, Vγ2Vδ2 type T cells treated by the same, and a medicine which comprises the same.